====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller-00176-g08ad43d554ba #0 Not tainted ------------------------------------------------------ syz-executor.2/28705 is trying to acquire lock: ffff88807c84b418 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0xa9/0x180 mm/memory.c:5645 but task is already holding lock: ffff88801f2660f8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x350 fs/btrfs/locking.c:134 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (btrfs-root-00){++++}-{3:3}: down_read_nested+0x9e/0x450 kernel/locking/rwsem.c:1634 __btrfs_tree_read_lock+0x32/0x350 fs/btrfs/locking.c:134 btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] btrfs_read_lock_root_node+0x82/0x3a0 fs/btrfs/locking.c:279 btrfs_search_slot_get_root fs/btrfs/ctree.c:1665 [inline] btrfs_search_slot+0x3ca/0x2c70 fs/btrfs/ctree.c:1985 btrfs_insert_empty_items+0xbd/0x1c0 fs/btrfs/ctree.c:4119 btrfs_insert_empty_item fs/btrfs/ctree.h:3127 [inline] insert_balance_item.isra.0+0x144/0x1460 fs/btrfs/volumes.c:3445 btrfs_balance+0xf5f/0x3be0 fs/btrfs/volumes.c:4351 btrfs_ioctl_balance fs/btrfs/ioctl.c:4481 [inline] btrfs_ioctl+0x115d/0x5be0 fs/btrfs/ioctl.c:5512 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #3 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x1b3/0x10f0 fs/btrfs/transaction.c:299 start_transaction+0x407/0x1470 fs/btrfs/transaction.c:658 btrfs_create_common+0x1aa/0x260 fs/btrfs/inode.c:6633 btrfs_create+0x116/0x160 fs/btrfs/inode.c:6679 lookup_open.isra.0+0xf05/0x12a0 fs/namei.c:3413 open_last_lookups fs/namei.c:3481 [inline] path_openat+0x996/0x2860 fs/namei.c:3710 do_filp_open+0x1ba/0x410 fs/namei.c:3740 do_sys_openat2+0x16d/0x4c0 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_sys_creat fs/open.c:1402 [inline] __se_sys_creat fs/open.c:1396 [inline] __x64_sys_creat+0xcd/0x120 fs/open.c:1396 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #2 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5382 [inline] lock_release+0x371/0x810 kernel/locking/lockdep.c:5688 percpu_up_read include/linux/percpu-rwsem.h:99 [inline] __sb_end_write include/linux/fs.h:1821 [inline] sb_end_intwrite include/linux/fs.h:1877 [inline] __btrfs_end_transaction+0x5c6/0x930 fs/btrfs/transaction.c:995 btrfs_dirty_inode+0x174/0x250 fs/btrfs/inode.c:6099 btrfs_update_time+0x25a/0x2c0 fs/btrfs/inode.c:6127 inode_update_time fs/inode.c:1871 [inline] __file_update_time fs/inode.c:2088 [inline] file_update_time+0x1fb/0x270 fs/inode.c:2119 btrfs_page_mkwrite+0x4f1/0x1140 fs/btrfs/inode.c:8431 do_page_mkwrite+0x19b/0x680 mm/memory.c:2978 do_shared_fault mm/memory.c:4619 [inline] do_fault mm/memory.c:4687 [inline] handle_pte_fault mm/memory.c:4955 [inline] __handle_mm_fault+0x2280/0x3a40 mm/memory.c:5097 handle_mm_fault+0x1cc/0x780 mm/memory.c:5218 do_user_addr_fault+0x475/0x1210 arch/x86/mm/fault.c:1428 handle_page_fault arch/x86/mm/fault.c:1519 [inline] exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1575 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570 -> #1 (sb_pagefaults#2){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1826 [inline] sb_start_pagefault include/linux/fs.h:1930 [inline] btrfs_page_mkwrite+0x1b5/0x1140 fs/btrfs/inode.c:8415 do_page_mkwrite+0x19b/0x680 mm/memory.c:2978 do_shared_fault mm/memory.c:4619 [inline] do_fault mm/memory.c:4687 [inline] handle_pte_fault mm/memory.c:4955 [inline] __handle_mm_fault+0x2280/0x3a40 mm/memory.c:5097 handle_mm_fault+0x1cc/0x780 mm/memory.c:5218 do_user_addr_fault+0x475/0x1210 arch/x86/mm/fault.c:1428 handle_page_fault arch/x86/mm/fault.c:1519 [inline] exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1575 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570 -> #0 (&mm->mmap_lock#2){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633 __might_fault mm/memory.c:5646 [inline] __might_fault+0x10c/0x180 mm/memory.c:5639 _copy_to_user+0x29/0x150 lib/usercopy.c:29 copy_to_user include/linux/uaccess.h:169 [inline] btrfs_ioctl_get_subvol_rootref+0x74e/0xad0 fs/btrfs/ioctl.c:3203 btrfs_ioctl+0x2de6/0x5be0 fs/btrfs/ioctl.c:5556 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Chain exists of: &mm->mmap_lock#2 --> btrfs_trans_num_extwriters --> btrfs-root-00 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(btrfs-root-00); lock(btrfs_trans_num_extwriters); lock(btrfs-root-00); lock(&mm->mmap_lock#2); *** DEADLOCK *** 1 lock held by syz-executor.2/28705: #0: ffff88801f2660f8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x350 fs/btrfs/locking.c:134 stack backtrace: CPU: 0 PID: 28705 Comm: syz-executor.2 Not tainted 6.1.0-rc6-syzkaller-00176-g08ad43d554ba #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177 check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633 __might_fault mm/memory.c:5646 [inline] __might_fault+0x10c/0x180 mm/memory.c:5639 _copy_to_user+0x29/0x150 lib/usercopy.c:29 copy_to_user include/linux/uaccess.h:169 [inline] btrfs_ioctl_get_subvol_rootref+0x74e/0xad0 fs/btrfs/ioctl.c:3203 btrfs_ioctl+0x2de6/0x5be0 fs/btrfs/ioctl.c:5556 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fa71908c0d9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fa719e0e168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fa7191ac050 RCX: 00007fa71908c0d9 RDX: 000000002005b180 RSI: 00000000d000943d RDI: 0000000000000004 RBP: 00007fa7190e7ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe49c525ef R14: 00007fa719e0e300 R15: 0000000000022000